Bridging the Interlayer Binding to Ordered π‐Conjugated Units for Constructing High‐Performing Light Polarization Crystals

Abstract The light polarization modulation involves the capacity to respond selectively to light‐mater interaction and is dependent on the optical anisotropy of crystalline materials. The π‐conjugated component is almost typically utilized to produce such materials in the short‐wave ultraviolet region; however, the conflicting link between high optical anisotropy and strong layered habit is difficult to reconcile. As a result, many anisotropic crystals are limited to tiny crystals rather than processing optical devices. This study designs crystals with beneficial but easy‐to‐grow layered structure and strong optical anisotropy by bridging the interlayer binding to ordered π‐conjugated units. To this end, two new hybrid crystals Na 2 [C(NH 2 ) 3 ][HCOO] 3 (1Na) and K 2 [C(NH 2 ) 3 ][HCOO] 3 (2K) are reported by combining cationic regulation and π‐conjugated units. The strong interlayer interaction and stable crystal structure of 1Na have been found to be caused by the orbital hybridization and Lewis acidity of Na + and [HCOO] groups. This allows for the easy growth of centimeter‐large, high optical quality 1Na single crystals, providing crystal assurance for all‐around testing for a practical crystal. Using the most accurate minimal deviation angle method, the birefringence is measured to be 0.174–0.258 @253‐1013 nm, surpassing all reported crystals with the same components of [HCOO] or [C(NH 2 ) 3 ] in the applied short‐wave ultraviolet region as well as the corresponding commercial crystals. More importantly, preliminary Glan–Taylor prism is designed to test its light polarization ability. This work will serve as a guide for future research on innovative short‐wave ultraviolet birefringent crystals.